- potions for strength, dexterity... have permanent effects? for what than are used mushrooms in AmberMoon (red and blue) ?!?
- I just found Alkems Ring, very nice item! is there any chance to duplicate it (where I can find duplicate/copy scroll?) or somehow not to give Alkems his ring but still get access to shop? I suppose I can find empty vial somewhere else?...

Those Potions have permanent effects though the outcome of how much they increase stats is random i think it was 1-5 points.
Mushrooms are needed later for a Quest.
Alkems Ring can't be duplicated in a normal way only by using the built in ingame "cheat". The shop can only be accessed if you give him the Ring which is the way this game is meant to be played. You will find empty potions elsewhere in game.